These are reed valves designed with flow corner and with calculed capacity section. The petals are made of a material composed of karbonit and carbon. They are manufactured with advanced production processes and with the use of raw materials carefully selected. These reed valves are designed for racing engines and they have been tested directly on race tracks. Compatible with: - Aprilia: SR 50 Min.AC 94-_S - Mbk: Booster 50 euro 0-1_S, Booster 50 euro 2_S, Stunt 50 euro 0-1_S, Stunt 50 euro 2_S - Yamaha: BW's 50 euro 0-1_S, BW's 50 euro 2_S